/
files.go
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/
files.go
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// +build linux darwin
/*
* btrfscue version 0.6
* Copyright (c)2011-2023 Christian Blichmann
*
* Device extent backed file implementation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package rescuefs
import (
cliutil "blichmann.eu/code/btrfscue/cmd/btrfscue/app/util"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/hanwen/go-fuse/v2/fuse/nodefs"
)
// Similar to stripeMapEntry in Index.Physical()
type extentMapEntry struct {
devID uint64 // Not yet used
offset uint64
length uint64
// TODO(cblichmann): Compression
}
type extentFile struct {
nodefs.File
fs *rescueFS
extentMap []extentMapEntry
}
func newExtentFile(fs *rescueFS, owner, id uint64) nodefs.File {
r, e := fs.ix.FileExtentItems(owner, id)
if !r.HasNext() {
return nil
}
f := &extentFile{
File: nodefs.NewReadOnlyFile(nodefs.NewDefaultFile()),
fs: fs,
extentMap: make([]extentMapEntry, 0, 1)}
for ; r.HasNext(); e = r.Next() {
dev, phys := fs.ix.Physical(e.DiskByteNr())
f.extentMap = append(f.extentMap, extentMapEntry{
devID: dev,
offset: phys,
length: e.DiskNumBytes()})
}
return f
}
func (f *extentFile) String() string {
return "extentFile"
}
func (f *extentFile) GetAttr(out *fuse.Attr) fuse.Status {
// TODO(cblichmann): Return the real attributes, esp. size
out.Mode = fuse.S_IFREG | 0644
out.Size = f.extentMap[0].length
return fuse.OK
}
func (f *extentFile) Read(buf []byte, off int64) (res fuse.ReadResult,
code fuse.Status) {
// TODO(cblichmann): Read more than the first extent
start := int64(f.extentMap[0].offset) + off
if uint64(off+int64(len(buf))) <= f.extentMap[0].length {
if _, err := f.fs.dev.ReadAt(buf, start); err != nil {
cliutil.Warnf("read error: \n", err)
}
} else {
cliutil.Warnf("read out of bounds: only first extent supported (up "+
"to %d bytes)\n", f.extentMap[0].length)
}
return fuse.ReadResultData(buf), fuse.OK
}